I would rather claim that building a theoretically secure system is prohibitively expensive. At the end of the day, Mythos et al. are just better tools for finding vulnerabilities that will eventually be available to both offensive and defensive actors.

If you imagine you had a vulnerability scanner as fast and convenient as a linter, it would be much cheaper to write secure code right away. Probably not perfectly secure, but still secure enough to make sure finding exploits stays expensive.